1610 Leeke und Nienburg: Morphologie der Gewebe (Anatomie) 1910. [37 



Generally onlj one of the archesporial cells becomes a true mother cell, 

 but occasionally as many as three may iunction as such. The non-functional 

 cells give rise to the tapetum. 



Tetrad formation takes place late in April. As a rule but one of the 

 Duclei resulting from the heterotypic division undergoes the homotypic division. 



The nucleus of the functional megaspore becomes separated from the 

 other nuclei in the mother cell by a membrane. 



The development of the femal gametophyte occupies about six vveeks. 



The megaspore membrane consists of two distinct layers. 



The tapetum persists until after the formation of prothallial tissue. 



From four to ten archegonia are organized, and, as in the other Ciipresseae, 

 these form a single complex which is surrounded by a layer of jacket cells. 



Peculiar aster-like structures, termed asteroids, are conspicuous in the 

 central cell of the archegonium and persist until after fertilization. Their 

 function is obscure. 



The division of the central cell nucleus takes place about three days 

 before fertilization and is approximately simultaneous in all the archegonia 

 of a group. The spindle of this division is apparently entirely of intra- 

 nuclear origin. 



A true ventral canal cell is never formed. The ventral canal nucleus 

 usually disintegrates, but sometimes persists for a longo time, and may divide 

 mitotically. 



In the mature egg nucleus the most conspicuous features are the nucleoli 

 and pseudonucleoli. Some of the latter are presumably related in some manner 

 to the chromatin. 



Fertilization takes place in June, and an interval of a week may elapse 

 between conjugation in different flowers on the same plant. 



Both male cells may be functional. 



The entire male cell may enter the egg, but frequently the cell mem- 

 brane is cast off outside. 



The male nucleus and the egg nucleus apparently fuse while in a 

 resting condition, and the fusion nucleus becomes surrounded by a mantle of 

 starch derived from the male cell. 



No distinction between male and female chromatin is apparent until the 

 Organisation of the spirems of the first segmentation division, vi^hen tvi'o se- 

 parate masses of chromatin may be clearly distinguished. 



The spindles of the first division of the fertilized egg and of the foUowing 

 divisions are intra-nuclear. 



Usually eight free nuclei are formed before the appearence of walls, 

 but in exceptional cases w^all development is delayed until after the fourth 

 nuclear division. 



Cell divisions in the upper tier of cells of the proembryo give rfse to 

 the suspensors and the cells of the rosette. Leeke. 



96. Wirz, H. Beiträge zur Entwicklungsgeschichte von Scia- 

 phila spec. und Epirrhizanthes elongata Bl. Flora N. F., 1, -l, 1910, p. 395 

 bis 446. Mit Taf. IV u. 22 Textabb.) 



Verf. gibt folgende Zusammenfassung der Resultate: 

 a) Epirrhanthes elongata Bl. 



1. In der zwitterigen Blüte entwickeln sich die Glieder in akropetaler 

 Reihenfolge. In den Antheren werden die Pollenurmutterzellen nach Ab- 



